Patent GB-400180-A (GB)
Title: Improvements in the manufacture of artificial threads, yarns and the like
IPC: D01D5/253
Filed: 1932-01-18
Abstract: For the production of artificial filaments of bulbous cross section, there is dissolved in the spinning solution a relatively non-volatile solid substance which is removed from the filaments subsequently to their production by the evaporative spinning method.  The proportion of the added substance is such that the solution contains at least 25 per cent of dissolved solids.  The addition may be made to solutions containing less or more than 25 per cent of the filament-forming material.  The added substance separates from the solution preferably during the very early stages of the setting process and is not removed from the filaments during their formation.  A substance more or less incompatible with the filament-forming material is chosen, and preferably it is soluble in water or other common solvent so that it may easily be removed.  The use of plasticizers, and substances such as resins, rubber-like bodies, and gelatine which are themselves capable of being spun into filaments, is excluded from the invention claimed.  The added substance may be an aliphatic hydroxy acid such as malic, citric, mandelic, tartaric, or tartronic acid, or a dicarboxylic acid such as oxalic, malonic, succinic, or glutaric acid, or an aromatic acid such as benzoic, or salicylic acid, or a salt of such acid, or an amino-acid such as alanine, valine, tyrosine, glycine, or phenyl glycine, or an inorganic salt such as ammonium bromide or nitrate, potassium iodide or bromide, calcium nitrate, magnesium bromide, or zinc chloride.  Substances such as anthracene and other hydrocarbons which are insoluble in water may be used provided that they can subsequently be removed by a solvent which is a non-solvent for the filament material.  The proportion of added substance may be varied within wide limits.  The presence of the added substance enables filaments of bulbous cross section to be obtained even at high spinning speeds.  To enhance the desired effect, water, highly volatile substances such as ether, or substances which increase the viscosity, may be added to the spinning solution. Low concentrations of cellulose esters or ethers of high viscosity characteristics may be employed.  The process is applicable to spinning solutions of cellulose nitrate, acetate or other cellulose ester, or ethyl cellulose or other cellulose ether, or mixed cellulose esters, ethers, or ether-esters.  During the spinning process, air or other gas may be blown or drawn across the filaments in the early stages of their formation. Specifications 210,108, 300,998, 304,674, 325,233, 326,232, 333,504, [all in Class 2 (ii), Cellulose &c.], 352,922, 385,617, 388,400, and 389,870, are referred to.  The Provisional Specification refers also to wet spinning processes and to the use of viscose and cuprammonium cellulose solutions; for wet spinning cellulose organic derivative solutions, the coagulating bath may be a hydrocarbon, or an oil.  Naphthalene is included as a substance which may be added to the spinning solution. Removal of the added substance from the formed filaments is not essential.